Free Disk Necessary To Retructure A File

[John Esak]

<top posted question about file size in re-define>

You are right, You have plenty to spare.

I hate working in MB's... much better to work with the actual byte size of
the files and not worrry about converting to millions and then dividing by
1024*1024, etc.  If you simply  add 20 to the 2837 (which you are heading
for, (because the Define files program does not display the extar 20 byte
header needed for each record), giving you 2857 and multiply this times
159,000 + 1 (for the extra 0th record which is also commonly forgotten...
you end up with 454265857 bytes of space needed to hold the new file... and
that is really all you need.

Ken wrote the Define Files routine that adds characters, to do it "in
place". In other words you just move the end of file marker to the highest
point the file will require after the new full size is calculated, and then
writing all the records one by one from the end of the file to their new
position starting backwards from the end of the file.  A nice, efficient way
to make a file bigger back in the days when disk space was at a huge
premium.  

So, you really have plenty of room for your addition.  

If you were to *shrink* the file on the other hand (take away characters
from any field), this trick is not employed so you would need the full new
size of the file in free space, at least, for the "temp" file which would be
created and then moved into place.

John



> -----Original Message-----
> From: filepro-list-bounces+john=valar.com at lists.celestial.com
> [mailto:filepro-list-bounces+john=valar.com at lists.celestial.com] On Behalf
> Of Scott Walker
> Sent: Saturday, July 26, 2008 3:25 PM
> To: 'filePro_List'
> Subject: Free Disk Necessary To Retructure A File
> 
> I just want to make sure...
> 
> I have a key file that is 436mb.
> 
> I am going to restructure it, changing the record length from 2735 to
> 2837
> 
> I have 159,000 records in this file.
> 
> I have 515mb of free disk space.
> 
> I think I have enough disk space to do this.
> 
> Am I right?
> 
> Regards,
> 
> 
> Scott
> 
> 
> Scott Walker
> RAM Systems Corp.
> ScottWalker at RAMSystemsCorp.com
> Ph: (704) 896-6549
> 
> 
> 
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